While it's true that Maybe's kind is (* -> *), there still may be a better answer to your question, which asks, "Is there a way to get a polykinded promoted type?" Maybe isn't polykinded, but it's also not promoted. With

data Proxy a = P

we get (Proxy :: k -> *). But that's not promoted either. On the other hand we have ('Just :: k -> Maybe k), which is promoted and polykinded, but maybe not what you want.

Does this help?

Richard

On Dec 8, 2014, at 5:52 PM, Gautier DI FOLCO <gautier.difolco@gmail.com> wrote:

Hi all,

Is there a way to get a Polykinded promoted type.
For example with Maybe I get:
data Maybe a = Just a | Nothing
Prelude> :k Maybe
Maybe :: * -> *

Is it possible to get a k -> *? If so, how can I do that?

Thanks in advance for your help,
Regards.
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